Live images (1)
These pages aim at displaying live star-test images and Aberrator equivalents.

The live-images are copyright by Roland Christen of Astrophysics.

Below on the left are the live-images (autocollimator) of a 5” APO-triplet. This particular lens were estimated 1/10 wave PV.  Using an autocollimator (2-pass system) the images should should show a 1/5 PV wavefront error.

In-focus

On the left the in-focus image of the triplet at the autocollimator, in the middle a simulation of  0.2 wave PV (1/5) lower spherical aberration(LSA) in focus and on the right a 0.1 wave LSA.

The image on the left is clearly over-exposed since the airy-disc looks uniform white and the gap between airy-disc and the first diffration ring is very thin.

First dark-point inner focus

The middle and right simulation images are at 0.85 wave of defocus for 0.2 and 0.1 PV LSA. Most of the light-distribution features are similar to the live-image except for the middle dot. The live image does not show this featurel.

2nd dark point inner focus

The simulated image on the right was made with 2.2 waves of defocus and 0.2 PV wave LSA, once more the main difference is the missing of the bright inner dot in the live image.